Determining the Relative Position Between a Point Cloud Generating Camera and Another Camera

2. The method of claim 1 wherein the identifying the 2D markers in the 3D point cloud uses the property that points on a non-reflective part of the planar surface are identified as having a larger distance to the second camera than points on the reflective part of the planar surface.

4. The method of claim 1 wherein the determining the relative position between the first camera and the second camera includes defining a first reference system for the first camera and a second reference system for the second camera and finding a transformation which transforms the 3D marker data from the second reference system into the first reference system such that all transformed locations of the 2D markers as represented by the transformed 3D marker data lie on lines in the first reference system corresponding to the 2D marker data.

7. The method of claim 6, wherein a plane is fitted into the points of the 3D point cloud which represent the planar surface of the phantom, a transformation describing rotations about axes perpendicular to the depth direction of the reference system of the second camera and making the plane perpendicular to said depth direction is calculated, the transformation is applied to the 3D point cloud and the inverse of the transformation is applied to the auxiliary 2D marker data.

8. The method of claim 6, wherein points of the 3D point cloud which do not lie on the plane are removed from the 3D point cloud.

9. The method of claim 6, wherein the 2D view is a depth map of the rotated 3D point cloud.

10. The method of claim 6, wherein the method for finding the 2D markers in the 2D view is the same as the method for finding the 2D markers in the 2D image.

11. The method of claim 1, wherein a deviation value of the relative position between the first camera and the second camera is calculated and wherein the determining the relative position between the first camera and the second camera is repeated if the deviation value is above a predetermined threshold.

12. The method of claim 11, wherein the 3D marker data is projected into the image plane of the first camera using the determined relative position and intrinsic parameters of the first camera, the distances between the locations of the markers of the projected 3D marker data in the image plane and the locations of the corresponding markers found in the 2D image are calculated and the deviation value is calculated from the said distances.

13. The method of claim 12, wherein the deviation value is the root mean square of the distances.

14. The method of claim 1, wherein a one-to-one correspondence between the markers in the 2D marker data and the 3D marker data is established.

15. The method of claim 1 wherein the medical phantom has a planar surface forming a background on which a plurality of the 2D markers are formed.

16. The method of claim 15 wherein the phantom includes a reflective area of the planar surface which is diffuse reflecting and a non-reflective area of the planar surface is specular reflecting or light absorbing.